Guinea pig L2C leukemia cells are harvested from the blood, spleen and lymph nodes of strain 2 animals injected with viable leukemic cells two weeks earlier. The cells are purified by gradient centrifugation and are disrupted by nitrogen cavitation. The plasma membranes are purified by differential and gradient centrifugation. The membranes will be solubilized with detergent and specific components will be isolated by affinity chromatography. BIBLIOGRAPHIC REFERENCES: Philippot, J.R., Cooper, A.G. and Wallach, D.F. Hoelzl. "A nitroxidesterol derivative potently modifies cholesterol biosynthesis by normal and neoplastic guinea pig lymphocytes". BBA Acta 406:161, 1975. Kobzik, L., Brown, M.C. and Cooper, A.G. "Demonstration of an idiotypic antigen on a monoclonal cold agglutinin and on its isolated heavy and light chains". PNAS, May 1976.